Electronics cooling

About: Electronics cooling is a research topic. Over the lifetime, 1135 publications have been published within this topic receiving 17608 citations.

Condenser bypass for two-phase electronics cooling system

Abstract: An electronics cooling system utilizing a refrigerant fluid that evaporates to remove heat from electronics and is condensed back to liquid through heat exchange with a cold medium (air or water). The refrigerant fluid is circulated via a liquid pump between the condenser and heated evaporators. A bypass circuit is provided to divert flow around the condenser during conditions of cold ambient temperatures, which is controlled by a feedback loop using a mechanical or electronic control valve. This prevents the refrigerant fluid temperature from becoming very low and potentially inducing condensation on the outside of the refrigerant tubing from the warm and moist indoor air.

CFD simulations of heat transfer from a heated module in an air stream: Comparison with experiments and a parametric study

Abstract: In the last decade or so, CFD simulations have become increasingly widely used in studies of electronic cooling. Validation of these simulations has been considered to be very important. Nakayama and Park (1994, 1996) have performed a series of experiments with the aim of measuring the heat transfer and flow field in the simple geometry of a heated chip in an air stream. They observed a number of complex features in both the flow field and heat transfer behaviour. In this study, their experimental geometry has been used to simulate the flow and temperature fields in a parallel-plate channel with a heated block mounted on the floor. The channel inlet flow velocity has been varied between 1 and 7 m/s. Various turbulence models have been tested, and the effect of the channel inlet flow on the heat transfer rate has been determined by considering both a uniform and fully-developed condition. The substrate adiabatic heat transfer coefficient is also numerically determined. The results indicate that the flow in the vicinity of the module is three-dimensional, and exhibits flow separation and vortex formation, hence leading to a complex distribution of the local heat transfer coefficient on the substrate. The air temperature next to the floor is strongly affected by the heat transfer from the block, which leads to the formation of a thermal wake downstream of the block. The experimental data is used to validate the CFD predictions and agreement for some parameters is shown to be favorable.

Heterostructure integrated thermionic refrigeration

Abstract: Thermionic emission in heterostructures is investigated for integrated cooling of high power electronic and optoelectronic devices. This evaporative cooling is achieved by selective emission of hot electrons over a barrier layer from the cathode to the anode. As the energy distribution of emitted electrons is almost exclusively on one side of Fermi energy, upon the current flow, strong carrier-carrier and carrier-lattice scatterings tend to restore the quasi equilibrium Fermi distribution in the cathode by absorbing energy from the lattice, and thus cooling the emitter junction. An analytic expression for the optimum barrier thickness is derived. It describes the interplay between Joule heating in the barrier and heat conduction from the hot to the cold junction. It is shown that by choosing a barrier material with high electron mobility and low thermal conductivity it is possible to cool electronic devices by 5 to 40 degrees in a wide range of temperatures.

Microcontact-Enhanced Thermoelectric Cooling of Ultrahigh Heat Flux Hotspots

Abstract: The dissipated power of insulated gate bipolar transistor and high electron mobility transistor amplifiers is typically nonuniform, resulting in areas of elevated temperature, or hotspots, which can have very large heat fluxes, on the order of 1000 W/cm2. While various bulk cooling systems are being researched to remove large amounts of heat, they uniformly reduce the chip temperature, leaving the temperature nonuniformity. Therefore, advanced hotspot cooling techniques, which provide localized cooling, are also required to unlock the full potential of cutting edge power devices. Thermoelectric coolers have previously been demonstrated as an effective method of producing on-demand cooling for the removal of localized hotspots. However, the heat flux of the hotspots that can be cooled is limited by the maximum cooling flux of thermoelectric devices. This paper demonstrates the thermal and reliability performance of a microcontact-enhanced thermoelectric cooling configuration, which uses a contact structure etched directly out of the electronic substrate to concentrate the cooling produced by a commercially available thermoelectric module. The 22 K of cooling, resulting in a hotspot temperature rise of <6 K for a heat flux of 2.5 kW/cm2, was experimentally demonstrated using a Laird HV37 thin-film thermoelectric module with a maximum device level cooling flux of 66 W/cm2. A numerical model was created, and it is predicted that when the chip and microcontact geometry is optimized, hotspots with heat fluxes in excess of 3 kW/cm2 can be cooled by nearly 40 K, reducing the hotspot temperature rise to 0 K.